📄 gsm_decode.c
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/*
GSM voice codec, part of the HawkVoice Direct Interface (HVDI)
cross platform network voice library
Copyright (C) 2001-2003 Phil Frisbie, Jr. (phil@hawksoft.com)
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
Or go to http://www.gnu.org/copyleft/lgpl.html
*/
/*
* Copyright 1992 by Jutta Degener and Carsten Bormann, Technische
* Universitaet Berlin. See the accompanying file "COPYRIGHT" for
* details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE.
*/
#include "private.h"
static gsmword gsm_FACd[8] = {18431, 20479, 22527, 24575, 26623, 28671, 30719, 32767};
static gsmword gsm_QLB[4] = {3277, 11469, 21299, 32767};
INLINE void Postprocessing(struct gsm_state *S, short *s)
{
int k;
gsmword msr = S->msr;
longword ltmp;
for(k = 160; k--; s++)
{
msr = *s + (gsmword)GSM_MULT_R( msr, 28672 ); /* Deemphasis */
*s = (short)(GSM_ADD(msr, msr) & 0xFFF8); /* Truncation & Upscaling */
}
S->msr = msr;
}
static void APCM_quantization_xmaxc_to_exp_mant(gsmword xmaxc, gsmword *exp_out,
gsmword *mant_out)
{
gsmword exp, mant;
exp = 0;
if(xmaxc > 15)
exp = (gsmword)(SASR(xmaxc, 3) - 1);
mant = (gsmword)(xmaxc - SASL( exp, 3 ));
if(mant == 0)
{
exp = -4;
mant = 7;
}
else
{
while(mant <= 7)
{
mant = (gsmword)(SASL(mant, 1) | 1);
exp--;
}
mant -= 8;
}
*exp_out = exp;
*mant_out = mant;
}
static void APCM_inverse_quantization(gsmword *xMc, gsmword mant, gsmword exp, gsmword *xMp)
{
int i;
gsmword temp, temp1, temp2, temp3;
longword ltmp;
temp1 = gsm_FACd[ mant ]; /* see 4.2-15 for mant */
temp2 = (gsmword)GSM_SUB( 6, exp ); /* see 4.2-15 for exp */
temp3 = (gsmword)SASL( 1, GSM_SUB( temp2, 1 ));
for(i = 13; i--;)
{
temp = (gsmword)(SASL(*xMc++, 1) - 7); /* restore sign */
temp = (gsmword)SASL(temp, 12); /* 16 bit signed */
temp = (gsmword)GSM_MULT_R( temp1, temp );
temp = (gsmword)GSM_ADD( temp, temp3 );
*xMp++ = (gsmword)SASR( temp, temp2 );
}
}
static void RPE_grid_positioning(gsmword Mc, gsmword *xMp, gsmword *ep)
{
int i = 13;
switch (Mc) {
case 3: *ep++ = 0;
case 2: do
{
*ep++ = 0;
case 1: *ep++ = 0;
case 0: *ep++ = *xMp++;
} while (--i != 0);
}
while(++Mc < 4)
*ep++ = 0;
}
static void Gsm_RPE_Decoding(gsmword xmaxcr, gsmword Mcr, gsmword *xMcr, gsmword *erp)
{
gsmword exp, mant;
gsmword xMp[ 13 ];
APCM_quantization_xmaxc_to_exp_mant(xmaxcr, &exp, &mant);
APCM_inverse_quantization(xMcr, mant, exp, xMp);
RPE_grid_positioning(Mcr, xMp, erp);
}
static void Decoding_of_the_coded_Log_Area_Ratios(gsmword *LARc, gsmword *LARpp)
{
gsmword temp1;
long ltmp;
#undef STEP
#define STEP( B, MIC, INVA ) \
temp1 = (gsmword)(SASL( *LARc++ + MIC , 10)); \
temp1 -= SASL( B, 1 ); \
temp1 = (gsmword)GSM_MULT_R( INVA, temp1 ); \
*LARpp++ = (gsmword)GSM_ADD( temp1, temp1 );
STEP( 0, -32, 13107 );
STEP( 0, -32, 13107 );
STEP( 2048, -16, 13107 );
STEP( -2560, -16, 13107 );
STEP( 94, -8, 19223 );
STEP( -1792, -8, 17476 );
STEP( -341, -4, 31454 );
STEP( -1144, -4, 29708 );
}
INLINE void Coefficients_0_12(gsmword * LARpp_j_1, gsmword * LARpp_j, gsmword * LARp)
{
int i;
for(i = 1; i <= 8; i++, LARp++, LARpp_j_1++, LARpp_j++)
{
*LARp = (gsmword)(SASR( *LARpp_j_1, 2 ) + SASR( *LARpp_j, 2 ));
*LARp += (gsmword)SASR( *LARpp_j_1, 1);
}
}
INLINE void Coefficients_13_26(gsmword * LARpp_j_1, gsmword * LARpp_j, gsmword * LARp)
{
int i;
for(i = 1; i <= 8; i++, LARpp_j_1++, LARpp_j++, LARp++)
*LARp = SASR( *LARpp_j_1, 1) + SASR( *LARpp_j, 1 );
}
INLINE void Coefficients_27_39(gsmword * LARpp_j_1, gsmword * LARpp_j, gsmword * LARp)
{
int i;
for(i = 1; i <= 8; i++, LARpp_j_1++, LARpp_j++, LARp++)
{
*LARp = (gsmword)(SASR( *LARpp_j_1, 2 ) + SASR( *LARpp_j, 2 ));
*LARp += (gsmword)SASR( *LARpp_j, 1 );
}
}
INLINE void Coefficients_40_159(gsmword * LARpp_j, gsmword * LARp)
{
int i;
for(i = 1; i <= 8; i++, LARp++, LARpp_j++)
*LARp = *LARpp_j;
}
static void LARp_to_rp(gsmword * LARp)
{
int i;
gsmword temp;
for (i = 1; i <= 8; i++, LARp++)
{
if (*LARp < 0)
{
temp = (gsmword)GSM_ABS( *LARp );
*LARp = (gsmword)(- ((temp < 11059) ? SASL( temp, 1 )
: ((temp < 20070) ? temp + 11059
: ( SASR( temp, 2 ) + 26112 ))));
}
else
{
temp = *LARp;
*LARp = (gsmword)((temp < 11059) ? SASL( temp, 1 )
: ((temp < 20070) ? temp + 11059
: ( SASR( temp, 2 ) + 26112 )));
}
}
}
static void Short_term_synthesis_filtering(struct gsm_state *S, gsmword *rrp, int k,
gsmword *wt, short *sr)
{
gsmword * v = S->v;
gsmword sri;
longword ltmp;
gsmword v0=v[0], v1=v[1], v2=v[2], v3=v[3],
v4=v[4], v5=v[5], v6=v[6], v7=v[7];
gsmword rrp0, rrp1, rrp2, rrp3,
rrp4, rrp5, rrp6, rrp7;
rrp0 = rrp[0]; rrp1 = rrp[1];
rrp2 = rrp[2]; rrp3 = rrp[3];
rrp4 = rrp[4]; rrp5 = rrp[5];
rrp6 = rrp[6]; rrp7 = rrp[7];
while(k-- != 0)
{
sri = *wt++;
sri -= (gsmword)GSM_MULT_R(rrp7, v7);
sri -= (gsmword)GSM_MULT_R(rrp6, v6);
v7 = v6 + (gsmword)GSM_MULT_R(rrp6, sri);
sri -= (gsmword)GSM_MULT_R(rrp5, v5);
v6 = v5 + (gsmword)GSM_MULT_R(rrp5, sri);
sri -= (gsmword)GSM_MULT_R(rrp4, v4);
v5 = v4 + (gsmword)GSM_MULT_R(rrp4, sri);
sri -= (gsmword)GSM_MULT_R(rrp3, v3);
v4 = v3 + (gsmword)GSM_MULT_R(rrp3, sri);
sri -= (gsmword)GSM_MULT_R(rrp2, v2);
v3 = v2 + (gsmword)GSM_MULT_R(rrp2, sri);
sri -= (gsmword)GSM_MULT_R(rrp1, v1);
v2 = v1 + (gsmword)GSM_MULT_R(rrp1, sri);
sri = (gsmword)GSM_SUB( sri, (gsmword)GSM_MULT_R(rrp0, v0) );
v1 = v0 + (gsmword)GSM_MULT_R(rrp0, sri);
v0 = sri;
*sr++ = (short)sri;
}
v[0]=GSM_ADD(v0, 0);
v[1]=GSM_ADD(v1, 0);
v[2]=GSM_ADD(v2, 0);
v[3]=GSM_ADD(v3, 0);
v[4]=GSM_ADD(v4, 0);
v[5]=GSM_ADD(v5, 0);
v[6]=GSM_ADD(v6, 0);
v[7]=GSM_ADD(v7, 0);
}
static void Gsm_Short_Term_Synthesis_Filter(struct gsm_state * S, gsmword *LARcr,
gsmword *wt, short *s)
{
gsmword * LARpp_j = S->LARpp[ S->j ];
gsmword * LARpp_j_1 = S->LARpp[ S->j ^=1 ];
gsmword LARp[8];
Decoding_of_the_coded_Log_Area_Ratios(LARcr, LARpp_j);
Coefficients_0_12(LARpp_j_1, LARpp_j, LARp);
LARp_to_rp(LARp);
Short_term_synthesis_filtering(S, LARp, 13, wt, s);
Coefficients_13_26(LARpp_j_1, LARpp_j, LARp);
LARp_to_rp(LARp);
Short_term_synthesis_filtering(S, LARp, 14, wt + 13, s + 13);
Coefficients_27_39(LARpp_j_1, LARpp_j, LARp);
LARp_to_rp(LARp);
Short_term_synthesis_filtering(S, LARp, 13, wt + 27, s + 27);
Coefficients_40_159(LARpp_j, LARp);
LARp_to_rp(LARp);
Short_term_synthesis_filtering(S, LARp, 120, wt + 40, s + 40);
}
static void Gsm_Long_Term_Synthesis_Filtering(struct gsm_state *S, gsmword Ncr, gsmword bcr,
gsmword *erp, gsmword *drp)
{
int k;
gsmword brp, Nr;
gsmword * pdrp;
Nr = (gsmword)(Ncr < 40 || Ncr > 120 ? S->nrp : Ncr);
S->nrp = Nr;
brp = gsm_QLB[ bcr ];
pdrp = drp;
for(k = 40; k--; pdrp++)
{
*pdrp = (gsmword)(*erp++ + GSM_MULT_R( brp, pdrp[ -(Nr) ] ));
}
memcpy(&drp[-120], &drp[-80], (sizeof(drp[0]) * 120));
}
static void Gsm_Decoder(struct gsm_state *S, gsmword *LARcr, gsmword *Ncr, gsmword *bcr,
gsmword *Mcr, gsmword *xmaxcr, gsmword *xMcr, short *s)
{
int j;
gsmword erp[40], wt[160];
gsmword * drp = S->dp0 + 120;
for(j=0; j <= 3; j++, xmaxcr++, bcr++, Ncr++, Mcr++, xMcr += 13)
{
Gsm_RPE_Decoding( *xmaxcr, *Mcr, xMcr, erp );
Gsm_Long_Term_Synthesis_Filtering( S, *Ncr, *bcr, erp, drp );
memcpy(&wt[ j * 40 ], drp, sizeof(drp[0]) * 40);
}
Gsm_Short_Term_Synthesis_Filter(S, LARcr, wt, s);
Postprocessing(S, s);
}
int gsm_decode ( struct gsm_state *s, unsigned char *c, short *target)
{
gsmword LARc[8], Nc[4], Mc[4], bc[4], xmaxc[4], xmc[13*4];
{
if(((*c >> 4) & 0x0F) != GSM_MAGIC)
return 0;
LARc[0] = (gsmword)((*c++ & 0xF) << 2); /* 1 */
LARc[0] |= (gsmword)((*c >> 6) & 0x3);
LARc[1] = (gsmword)(*c++ & 0x3F);
LARc[2] = (gsmword)((*c >> 3) & 0x1F);
LARc[3] = (gsmword)((*c++ & 0x7) << 2);
LARc[3] |= (gsmword)((*c >> 6) & 0x3);
LARc[4] = (gsmword)((*c >> 2) & 0xF);
LARc[5] = (gsmword)((*c++ & 0x3) << 2);
LARc[5] |= (gsmword)((*c >> 6) & 0x3);
LARc[6] = (gsmword)((*c >> 3) & 0x7);
LARc[7] = (gsmword)(*c++ & 0x7);
Nc[0] = (gsmword)((*c >> 1) & 0x7F);
bc[0] = (gsmword)((*c++ & 0x1) << 1);
bc[0] |= (gsmword)((*c >> 7) & 0x1);
Mc[0] = (gsmword)((*c >> 5) & 0x3);
xmaxc[0] = (gsmword)((*c++ & 0x1F) << 1);
xmaxc[0] |= (gsmword)((*c >> 7) & 0x1);
xmc[0] = (gsmword)((*c >> 4) & 0x7);
xmc[1] = (gsmword)((*c >> 1) & 0x7);
xmc[2] = (gsmword)((*c++ & 0x1) << 2);
xmc[2] |= (gsmword)((*c >> 6) & 0x3);
xmc[3] = (gsmword)((*c >> 3) & 0x7);
xmc[4] = (gsmword)(*c++ & 0x7);
xmc[5] = (gsmword)((*c >> 5) & 0x7);
xmc[6] = (gsmword)((*c >> 2) & 0x7);
xmc[7] = (gsmword)((*c++ & 0x3) << 1); /* 10 */
xmc[7] |= (gsmword)((*c >> 7) & 0x1);
xmc[8] = (gsmword)((*c >> 4) & 0x7);
xmc[9] = (gsmword)((*c >> 1) & 0x7);
xmc[10] = (gsmword)((*c++ & 0x1) << 2);
xmc[10] |= (gsmword)((*c >> 6) & 0x3);
xmc[11] = (gsmword)((*c >> 3) & 0x7);
xmc[12] = (gsmword)(*c++ & 0x7);
Nc[1] = (gsmword)((*c >> 1) & 0x7F);
bc[1] = (gsmword)((*c++ & 0x1) << 1);
bc[1] |= (gsmword)((*c >> 7) & 0x1);
Mc[1] = (gsmword)((*c >> 5) & 0x3);
xmaxc[1] = (gsmword)((*c++ & 0x1F) << 1);
xmaxc[1] |= (gsmword)((*c >> 7) & 0x1);
xmc[13] = (gsmword)((*c >> 4) & 0x7);
xmc[14] = (gsmword)((*c >> 1) & 0x7);
xmc[15] = (gsmword)((*c++ & 0x1) << 2);
xmc[15] |= (gsmword)((*c >> 6) & 0x3);
xmc[16] = (gsmword)((*c >> 3) & 0x7);
xmc[17] = (gsmword)(*c++ & 0x7);
xmc[18] = (gsmword)((*c >> 5) & 0x7);
xmc[19] = (gsmword)((*c >> 2) & 0x7);
xmc[20] = (gsmword)((*c++ & 0x3) << 1);
xmc[20] |= (gsmword)((*c >> 7) & 0x1);
xmc[21] = (gsmword)((*c >> 4) & 0x7);
xmc[22] = (gsmword)((*c >> 1) & 0x7);
xmc[23] = (gsmword)((*c++ & 0x1) << 2);
xmc[23] |= (gsmword)((*c >> 6) & 0x3);
xmc[24] = (gsmword)((*c >> 3) & 0x7);
xmc[25] = (gsmword)(*c++ & 0x7);
Nc[2] = (gsmword)((*c >> 1) & 0x7F);
bc[2] = (gsmword)((*c++ & 0x1) << 1); /* 20 */
bc[2] |= (gsmword)((*c >> 7) & 0x1);
Mc[2] = (gsmword)((*c >> 5) & 0x3);
xmaxc[2] = (gsmword)((*c++ & 0x1F) << 1);
xmaxc[2] |= (gsmword)((*c >> 7) & 0x1);
xmc[26] = (gsmword)((*c >> 4) & 0x7);
xmc[27] = (gsmword)((*c >> 1) & 0x7);
xmc[28] = (gsmword)((*c++ & 0x1) << 2);
xmc[28] |= (gsmword)((*c >> 6) & 0x3);
xmc[29] = (gsmword)((*c >> 3) & 0x7);
xmc[30] = (gsmword)(*c++ & 0x7);
xmc[31] = (gsmword)((*c >> 5) & 0x7);
xmc[32] = (gsmword)((*c >> 2) & 0x7);
xmc[33] = (gsmword)((*c++ & 0x3) << 1);
xmc[33] |= (gsmword)((*c >> 7) & 0x1);
xmc[34] = (gsmword)((*c >> 4) & 0x7);
xmc[35] = (gsmword)((*c >> 1) & 0x7);
xmc[36] = (gsmword)((*c++ & 0x1) << 2);
xmc[36] |= (gsmword)((*c >> 6) & 0x3);
xmc[37] = (gsmword)((*c >> 3) & 0x7);
xmc[38] = (gsmword)(*c++ & 0x7);
Nc[3] = (gsmword)((*c >> 1) & 0x7F);
bc[3] = (gsmword)((*c++ & 0x1) << 1);
bc[3] |= (gsmword)((*c >> 7) & 0x1);
Mc[3] = (gsmword)((*c >> 5) & 0x3);
xmaxc[3] = (gsmword)((*c++ & 0x1F) << 1);
xmaxc[3] |= (gsmword)((*c >> 7) & 0x1);
xmc[39] = (gsmword)((*c >> 4) & 0x7);
xmc[40] = (gsmword)((*c >> 1) & 0x7);
xmc[41] = (gsmword)((*c++ & 0x1) << 2);
xmc[41] |= (gsmword)((*c >> 6) & 0x3);
xmc[42] = (gsmword)((*c >> 3) & 0x7);
xmc[43] = (gsmword)(*c++ & 0x7); /* 30 */
xmc[44] = (gsmword)((*c >> 5) & 0x7);
xmc[45] = (gsmword)((*c >> 2) & 0x7);
xmc[46] = (gsmword)((*c++ & 0x3) << 1);
xmc[46] |= (gsmword)((*c >> 7) & 0x1);
xmc[47] = (gsmword)((*c >> 4) & 0x7);
xmc[48] = (gsmword)((*c >> 1) & 0x7);
xmc[49] = (gsmword)((*c++ & 0x1) << 2);
xmc[49] |= (gsmword)((*c >> 6) & 0x3);
xmc[50] = (gsmword)((*c >> 3) & 0x7);
xmc[51] = (gsmword)(*c & 0x7); /* 33 */
}
Gsm_Decoder(s, LARc, Nc, bc, Mc, xmaxc, xmc, target);
return GSM_SAMPLES_PER_FRAME;
}
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